Valve replacement is the most common surgical procedure in patients with structural heart disease. Approximately 87,000 valve replacement procedures were performed in the U.S. during the year 2000. Replacement valves commonly used in valve replacement procedures are typically either artificial valves or tissue valves made from animal tissues.
To avoid immunological rejection of valves made from animal tissues, tissue valves are commonly treated to crosslink collagen in order to mask the antigen sites of animal cells, thereby relying on the cartilaginous structural matrix of the heart valve. Recently, tissue engineering has been used to develop replacement tissue valves featuring a structural matrix seeded with cells harvested from a putative recipient for a valve transplant patient. The structural matrix may either be a decellularized donor valve, or an artificial matrix constructed of man-made materials.
Tissue-engineered heart valves are typically re-cellularized by seeding the heart valve structural matrix with cardiac myo-fibroblasts or multi-potential cells such as adult stem cells from bone marrow or circulating endothelial proginator cells to enhance the structural strength of the valve, followed by a seeding with endothelial cells in order to develop a thrombosis-resistant surface on the tissue valve. In order to provide the appropriate conditions for the attachment, growth, and proliferation of the seeded cells, a bioreactor is typically used. In the chamber of the bioreactor, living cells are contacted with the valve's structural matrix under conditions conducive to the adhesion of the fibroblasts and endothelial cells to the matrix. Because certain tissues, such as heart valves, may have end portions that provide little space for engagement to the bioreactor, it can be difficult to adequately secure the heart valve to the bioreactor, without damaging structural components of the semilunar valve mechanism (e.g., annula, leaflets, commissures, etc.). In addition, the difference in size between adult and children's heart valves requires a tissue retention system that can accommodate different size heart valves. Further, it is desirable that the heart valve be retained in the bioreactor in a non-destructive manner.
Therefore, a need in the art exists for an improved tissue retaining system and related method of use that overcomes the drawbacks of the prior art.